1. Field of the Invention
The present invention relates to a method and system for operation of a resilient closed communication network without a dedicated protection network segment. The invention uses a plurality of devices and software to provide a resilient closed communication network.
2. Discussion of the Related Art
New transmission technologies and a wide-scale deployment of WDM (Wavelength Division Multiplexing) system carrying many independent traffic channels over the same fiber have resulted in a dramatic increase in traffic capacities of fiber optic network systems. For example, transmission links up to bit rates of 10 Gbps are in commercial service and new developments in multi-wavelength component technologies are resulting in increased commercial availability of 4-, 8-, 16-, 32-, and 40 channel WDM links.
Fiber optic network systems have been used widely in the area of communications. Their applications include: (1) a long-haul telecommunication systems on land and at sea such as ocean-spanning submarine cables and national backbone networks, to carry digitized signals simultaneously over a long distance; (2) interoffice trunks that carry many telephone conversations simultaneously between local and regional telephone switching facilities; (3) connections to Internet service providers; and (4) local-area networks.
Fiber optic network systems are vulnerable to a failure due to a breaking of an optical fiber. For example, fibers can be accidentally cut by operators not aware of their presence. Aerial cables are broken by falling branches and errant cranes. Submarine cables are cut by fishermen engaged in deep-sea fishing activities or by anchors.
Because the amount of information exchanged in a fiber optic network system is very high, a failure can have severe consequences in that a very high number of network users can be deprived of an information flow. In the past, some systems rerouted the traffic to alternative communication systems, such as satellite communication systems, in case of failure. However, satellite communication systems cannot handle a large amount of traffic handled by high-capacity fiber optic network systems. To deal with a network failure, some fiber optic communication systems rely on a dedicated protection ring or network segment, to which the traffic is switched from a failed working communication ring or network segment.
Protection rings or network segments provisioned for a dynamic restoration of service need provide a similar magnitude of capacity as working rings or network segments to serve as an effective backup or spare links for ensuring network survivability. This means that as much as a half of an available network capacity need be set aside as a protection against a network failure.
Besides high-capacity fiber optic network systems, other network system, such as those using T1 cables, often feature redundant connections to protect themselves from a failure. For example, they may use a dedicated protection ring or network segment. Alternatively, they may enforce connections between nodes by adding alternatively routes or duplicate routes. These redundant connections, however, increase a cost or building and maintaining network systems.
Thus, there is a need for providing a resilient closed network capable of automatically handling a network failure without using a protection ring or network segment and without relying on alternative communication systems such as satellite communication systems or redundant connections.